Heart stone



FIG. 1 is a top, front, and right side perspective view of a heart stone;

FIG. 2 is a bottom, rear, and left side perspective view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a bottom view thereof;

FIG. 5 is a right side view thereof, the left side view being a mirror image thereof;

FIG. 6 is a front side view thereof; and,

FIG. 7 is a rear side view thereof.

The broken lines in FIGS. 1, 2, 4, 5, 6, and 7 depict portions of the heart stone that form no part of the claimed design. 

CLAIM We claim the ornamental design for a heart stone, as shown and described. 